Awesome looking snake. And its looking to me like some sort of garter. You can clearly see a dorsal stripe on it as well as some side stripes. And you can see the brown zig-zagging its way up the sides there. Maybe a combination of genes in there? I'm not real big on garter genetics, but I am pretty good with corns. Looks to me like it could be similar to around a butter corn snake which is the combination of amelanistic and caramel or an amber which is the combination of hypo and caramel.

Looking at it a bit more, though, maybe its some sort of intergrade or hybrid? While all of the patterning and everything sure looks like a garter to me, that head is just slightly off from what I can see. Almost looks like the head's just not quite... I guess wide enough?